ADU Builder in Lafayette, CA
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Lafayette's Three ADU Classes
Lafayette sorts ADUs into three classes, and the class decides how simple your permit is. All three are approved ministerially, with no public hearing, and the City decides within 60 days of a complete application (Lafayette Municipal Code ยง6-563 and following, updated by Ordinance 695 in December 2024).
- Class A, detached: up to 800 sq ft, 16 feet tall, 4-foot side and rear setbacks.
- Class B, conversion: inside existing or proposed space, plus up to 150 sq ft for entry or exit.
- Class C, everything else: up to 1,200 sq ft with an ADU Permit. An attached unit is capped at 50% of the home’s floor area unless an exception applies. Height is 17 feet in general, 18 feet near transit (20 with a matching roof pitch), and an attached ADU can reach 25 feet or the zone limit, two stories maximum.
A junior ADU of up to 500 sq ft can sit inside the home with an efficiency kitchen; the owner must live on site when there is a JADU.
From Framing to Finish
Lafayette Design and Parking Rules
- Materials and colors must match the main house.
- Exterior lighting must be shielded and point down.
- An ADU entrance visible from the street cannot face the same direction as the main entrance.
- Any tree removed must be replaced with a 15-gallon tree.
- One 10-by-20-foot parking space for an ADU with a bedroom, using the existing curb cut, unless an exemption applies.
- Rentals must be 30 days or longer, with a recorded deed restriction.
Getting an ADU Permit in Lafayette
3675 Mt. Diablo Blvd., Suite 210, Lafayette, CA 94549
City Hall (925) 284-1968 · Planning (925) 284-1976
Zoning plan check is submitted online through the City’s idtPlans portal. Counter time is limited and Fridays are by appointment only, so book ahead.
- Zoning plan check with the City through idtPlans: site plan, floor plans and elevations.
- Central San review if the work affects sewer.
- Contra Costa County Fire Protection District review if applicable.
- County building plan check after the City stamps the drawings.
- County inspections and final.
Lafayette contracts with the County for plan check and inspection. Submit the City-stamped plans digitally through the County ePermits Center. County offices: 30 Muir Road, Martinez · (925) 655-2700. Inspections: ePermits or (925) 646-4108.
Lot Conditions to Check
- Native trees: oaks, bay, buckeye and madrone with a 12-inch trunk are protected on developed lots, and smaller trees are protected within 30 feet of a creek bank. A Category II tree permit must be decided before a building permit is issued.
- Septic: some Lafayette homes are on septic. An ADU connecting to an onsite system needs a percolation test.
- Creeks: creek-side work needs a creek setback determination.
- Utilities: EBMUD water, Central San sewer, PG&E power.
Explore More
Other Lafayette services: Bathrooms · Kitchens · Additions · New Homes · Lafayette overview
Same service nearby: Orinda · Moraga · Walnut Creek
Read how to build a backyard ADU or garage conversion requirements.
Lafayette ADU FAQ
How big can an ADU be in Lafayette?
A Class A detached ADU is up to 800 sq ft. A Class C ADU can be up to 1,200 sq ft, and an attached one is generally capped at 50% of the home. A junior ADU is up to 500 sq ft.
Does a Lafayette ADU need a public hearing?
No. All ADUs in Lafayette are reviewed ministerially, and the City decides within 60 days of a complete application.
Who inspects an ADU in Lafayette?
Contra Costa County performs plan check and inspections under contract with the City.
Do I need parking for my Lafayette ADU?
One 10-by-20-foot space for an ADU with a bedroom, unless an exemption applies, such as being near transit or converting a garage.